Experimental Study Of Electronically Controlled Common Rail Engine Operated With DME Fuel

Currently, the development of internal combustion engine industry is confronted with two aspects of pressure on energy crisis and environmental pollution. It has been required more on the performance, fuel economy and emissions of internal combustion engine due to the shortage of oil resources and increasingly stringent emission regulations. As a kind of coal-based alternative fuels, dimethyl ether is more suitable for the application on the compression ignition engine replacing diesel fuel due to the advantages of high cetane number, low boiling point and molecular structure of oxygen. As a consequence, it is beneficial for the reduction of NOx emissions and achievable for zero carbon smoke emission. Besides, Clean combustion could be achieved.The program allow the original machine to adapt the dimethyl ether fuel through the diesel modification by taking advantage of an electronically controlled common rail dimethyl ether engine as the research object. Considering the characteristics of easy-gasification and low viscosity, dimethyl ether fuel supply systems are designed and installed, including low pressure oil supply system and the high pressure common rail injection system. Electronically controlled common rail dimethyl ether engine test bench is set up.According to the control requirements of compression ignition engine electronic control injection system control, this experiment research the selection of injection parameters in the system based on the adoptive electronically controlled common rail engine operated with DME fuel. It is proved that dynamic performance of the electronically controlled common rail dimethyl ether engine fulfill the requirements through the external characteristic experiment of engine test bench. Electronically controlled common rail dimethyl ether engine external characteristic curve is more adaptable for the original machine compared with the diesel original machine and dimethyl ether engine mechanical inline pump. Emission characteristics of electronic control common rail DME engine is researched with circulatory bench test of ESC steady thirteen conditions. Comparing with experimental results from DME engine equipped with inline pump, emissions of CO and HC from electronic control common rail DME engine is lower. However, emission of NOx still need optimization.In order to decrease the emission of NOx, an external EGR system, which is applicable to Emission characteristics of electronic control common rail DME engine, is designed. Parameters of EGR cooler is adjusted to drainage Exhaust gas behind turbine but before compressor. Through external characteristics bench test using EGR system, the effect of EGR system on dynamic performance is researched:with EGR rate increasing, the power of engine reduce. Through load bench test on speed of 2300r/min, effects of EGR system on fuel economy is researched:EGR rate has less influence on fuel economy at light and medium load; at high load, the consumption of dimethyl ether increase with the adding of EGR rate. Low EGR rate is favorable for combustion and decrease of dimethyl ether consumption. Through circulatory bench test of ESC steady thirteen conditions, effects of EGR rate on emission characteristics of electronic control common rail DME engine is studied: the emission of NOx show an obvious tendency decrease after using EGR system and with the adding of EGR rate, the mission of NOx decrease more rapidly while the emission of CO increase. High EGR rate lead to obvious rise of CO emission and light rise of HC emission, but as a whole, the level of emission is still low.